// sample code showing two-dimensional arrays with [] and vector<>

#include <iostream>
#include <vector>
#include <iomanip>
using namespace std;

int constexpr WIDTH = 8, HEIGHT = 4;

// filling both types - these illustrate prototypes for 2d arrays
// Like all arrays, if you fill in the first dimension, that size is ignored. However,
// the sizes of all *other* dimensions are required.
void fill(int matrix[][WIDTH]);     // initialize table to sum of indices of each element

// The vector solution has no special rules; they are just objects (though a typedef
//    would likely be useful here)
void fill(vector<vector<int>> &);   // initialize table to product of indices of each elt.

// illustrates declearing a 2d array: HEIGHT rows, each row with WIDTH elements
void test_plain_2d_array() {
    int plain_array[HEIGHT][WIDTH]; // note the two dimensions listed separately
    // warning: writing [HEIGHT, WIDTH] would give *just* WIDTH (, as an operator)

    fill(plain_array); // calls array version; arrays are passed by reference!
    // write it out to confirm the data was set:
    cout << "Array-based table (each element is the sum of its indices):" << endl;
    for(int row = 0; row < HEIGHT; ++row) {
        for(int col = 0; col < WIDTH; ++col)
           // setw makes each element be written in 3 spaces and must be inserted
           //   into the output stream before each element (it resets after
           //   something is printed)
           cout << " " << setw(3) << plain_array[row][col];
        cout << endl;
    }
}

void fill(int matrix[][WIDTH])
{
    for(int row = 0; row < HEIGHT; ++row)
        for(int col = 0; col < WIDTH; ++col)
            matrix[row][col] = row + col;
}

// illustrates creating a vector of vectors. 
void test_vector_based_2d_table() {
    vector<vector<int>> vect(HEIGHT); // HEIGHT vectors, each will have size 0
    for(int i = 0; i < HEIGHT; ++i)
        vect[i].resize(WIDTH);        // resize each row to size WIDTH
    fill(vect); // call vector version, noting the parameter is passed by reference
    cout << "Vector-based table (each element is the product of its indices):" << endl;
    for(int row = 0; row < HEIGHT; ++row) {
        for(int col = 0; col < WIDTH; ++col)
            // use .at() to reference element, though [] would work as well!
            // setw makes each element be written in 3 spaces (right-justified)
            cout << " " << setw(3) << vect.at(row).at(col);
        cout << endl;
    }
}

void fill(vector<vector<int>> &vect)
{
    for(int row = 0; row < HEIGHT; ++row)
        for(int col = 0; col < WIDTH; ++col)
            vect[row][col] = row * col;
}

int main() {
    test_plain_2d_array();
    cout <<  "----------------------------------------" << endl;
    test_vector_based_2d_table();
    return 0;
}